Overview
EN ISO 105-B05:1995 / ISO 105-B05:1993 specifies a standardized test method for detecting and assessing photochromism in textiles - reversible colour changes that occur on brief exposure to intense light but that largely revert in the dark. The method identifies whether a coloured textile shows temporary light-induced colour change and quantifies its degree using the ISO grey scale for change in colour. The procedure is intended for quality control, specification and compliance testing within the textile industry.
Key topics and requirements
- Scope: Applies to coloured textiles that change shade on light exposure but return to original shade in darkness.
- Test principle: Expose a specimen to high-intensity light for a short time (much less than needed for permanent change), assess colour change immediately with the grey scale, then store in the dark and reassess.
- Specimen size: Minimum area 10 mm × 45 mm (strip or yarn pack).
- Light source: Xenon arc lamp with correlated colour temperature of 5 500 K to 6 500 K.
- Filter: A filter must reduce the UV component; transmission of the glass shall be at least 90% between 380 nm and 750 nm and fall to 0% between 310 nm and 320 nm.
- Reference materials: Uses Reference 1 or Reference L2 (as defined in ISO 105-B01) to determine exposure time required to produce a grey scale grade 4 change.
- Exposure timing: Specimen exposure is scaled to the time needed to produce a grade 4 fade on the reference (e.g., one-quarter or one-twenty-fifth of that time).
- Assessment and criteria:
- If immediate contrast ≤ grey scale grade 4 → specimen not photochromic.
- If immediate contrast > grade 4 but after dark-storage/conditioning reduces to ≤ grade 4–5 → specimen is photochromic.
- If contrast remains > grade 4–5 after conditioning → not photochromic but indicates low initial light fastness.
- Recovery acceleration: Steam treatment (60 s over boiling water on mesh) can be used to accelerate colour restoration before reassessment.
- Reporting format: Light fastness rating (from ISO 105-B01/B02) followed by the letter P and the grey-scale rating in brackets, e.g. 6(P3-4).
Applications and users
- Textile manufacturers and dye houses for product development and dye selection.
- Independent test laboratories and quality-control departments for compliance testing.
- Retailers and specifiers assessing temporary light responsiveness of dyed textiles (e.g., fashion, upholstery, technical textiles).
- Standards writers and regulatory bodies referencing consistent methods for photochromism assessment.
Related standards
- ISO 105-B01 / EN ISO 105-B01: Colour fastness to light (daylight) - reference exposure procedures.
- ISO 105-B02: Colour fastness to artificial light (Xenon arc).
- ISO 105-A01 / A02: General testing principles and grey scale for assessing change in colour.
Keywords: EN ISO 105-B05, ISO 105-B05:1993, photochromism, textiles, colour fastness, grey scale, Xenon arc lamp, light fastness testing.